Desulfogranum gen. nov .

Abstract

Abstract De.sul.fo.gra'num. L. pref. de , from; L. neut. n. sulfur , sulfur; N.L. pref. desulfo ‐, prefix used to characterize a dissimilatory sulfate‐reducing prokaryote; L. neut. n. granum , grain; N.L. neut. n. Desulfogranum , a sulfate‐reducing grain. Desulfobacterota / Desulfobulbia / Desulfobulbales / Desulfobulbaceae / Desulfogranum gen. nov. Oval‐shaped rods, 0.8–1.7 × 1.0–3.2 μm. Occur singly or in pairs. Spore formation is not observed. Gram‐stain‐negative. Motility might occur depending on the species. Anaerobic, having a respiratory and fermentative type of metabolism. Chemoorganoheterotrophic, using propionate, ethanol, propanol, lactate, and pyruvate as carbon sources and electron donors. Some species can use mono‐ and disaccharides. Electron donors are incompletely oxidized to acetate. For growth on H 2 + CO 2 (chemolithoheterotrophic growth) and formate, yeast extract or acetate is required. Sulfate and thiosulfate serve as terminal electron acceptors and are reduced to sulfide; sulfite is used by some species. Fermentative growth on pyruvate (all species) and sugars (some species). Mesophilic, with an optimal growth temperature between 25 and 35°C. Neutrophilic, with optimal pH range 6.7–7.5. All species show optimal growth in media with 20–30 g/l of NaCl. Media containing a reductant are necessary for growth. Vitamins or yeast extract seems to be required for growth of some species. Three former members of the genus Desulfobulbus are here reclassified as a new genus Desulfogranum within the family Desulfobulbaceae . Desulfogranum species occur in anoxic marine and brackish water sediments. DNA G + C content (mol%) : 45.8–57.5 (genome). Type species : Desulfogranum mediterraneum comb. nov. (basonym: Desulfobulbus mediterraneus Sass et al. 2002, VL87).